#pragma once
#include<iostream>
#include<assert.h>

namespace my_vector
{
	template<class T>
	class vector
	{
	public:
		typedef T* iterator;
		typedef const T* const_iterator;

		iterator begin()
		{
			return _start;
		}
		iterator end()
		{
			return _finish;
		}
		const_iterator begin() const
		{
			return _start;
		}
		const_iterator end() const
		{
			return _finish;
		}
		vector()
			:_start(nullptr)
			, _finish(nullptr)
			, _end_of_storage(nullptr)
		{}
		~vector()
		{
			if (_start)
			{
				delete[] _start;
				_start = _finish = _end_of_storage = nullptr;
			}
		}
		size_t size() const
		{
			return _finish - _start;
		}
		size_t capacity() const
		{
			return _end_of_storage - _start;
		}
		void push_back(const T& x)
		{
			if (_finish == _end_of_storage)
			{
				size_t newcapacity = (capacity() == 0 ? 4 : capacity() * 2);
				reserve(newcapacity);
			}
			*_finish = x;
			++_finish;
		}
		iterator insert(iterator pos, const T& x)
		{
			assert(pos >= _start && pos <= _finish);
			if (_finish == _end_of_storage)
			{
				size_t len = pos - _start;
				size_t newcapacity = (capacity() == 0 ? 4 : capacity() * 2);
				reserve(newcapacity);
				pos = _start + len;
			}
			iterator end = _finish - 1;
			while (end > pos)
			{
				*(end + 1) = *end;
				end--;
			}
			*pos = x;
			++_finish;

			return pos;
		}
		void reserve(size_t n)
		{
			if (capacity() < n)
			{
				size_t sz = size();
				T* tmp = new T[n];
				if (_start)
				{
					memcpy(tmp, _start, sizeof(T) * sz);
					delete[] _start;
				}
				_start = tmp;
				_finish = _start + sz;
				_end_of_storage = _start + n;
			}
		}
		T& operator[](size_t pos)
		{
			assert(pos < size());

			return _start[pos];
		}
		const T& operator[](size_t pos) const
		{
			assert(pos < size());

			return _start[pos];
		}
	private:
		iterator _start;
		iterator _finish;
		iterator _end_of_storage;
	
	};
}
